1. Field of the Invention
The present invention relates to a technique that optimizes the communication condition of a wide band wireless communication system with which an electronic appliance is in compliance depending on the communication condition of the country or region where the electronic appliance is used.
In addition, the invention includes an electronic appliance, a communication condition setting device, a communication condition setting method and a computer program.
2. Description of the Related Art
In recent years, in the field of wireless communications, an UWB (Ultra Wideband) wireless communication system is becoming widely available as one of prominent communication systems. The UWB wireless communication system has been developed for military purposes in the United States in the first place, and then opened to private sectors.
In the other wireless communication systems, the frequency bandwidth of a single channel is about several tens of MHz, whereas in the UWB wireless communication system, a frequency bandwidth of 3.1 GHz to 10.6 GHz is used. On this account, in the UWB wireless communication system, a large capacity of data can be transmitted at high speed.
The UWB wireless communication system has the characteristics that the radiation power level in frequency bands is very low and no interference occurs with other systems. In addition, the UWB wireless communication system also has the characteristics that power consumption is small.
With these characteristics, the UWB wireless communication system is used for a sensor using a position determination function, a radar using an object sensing function, and wireless communications between electronic appliances, for example.
In recent years, the influence of electromagnetic waves emitted from an electronic appliance upon other appliances is perceived as a problem.
This influence is referred to as electromagnetic interference (EMI), and mainly two types of transmission forms are considered. One of them is radiation interference waves (extraneous emissions) that are directly emitted from an electronic appliance to space, and the other is conducted interference waves that conduct through an AC (alternating current) power source line. Particularly, it is considered to be more important to take measures against the radiation interference waves emitted from various circuits configuring an electronic appliance at the same time.
Today, efforts for the EMI standard are conducted across the world. For example, in many countries, the rules compliant to the standards of the Comite International Special des Perturbations (CISPR) that is an international organization, and the import and sales of electronic appliances violating the limit values are banned.
For example, in Japan, there is the VCCI (Voluntary Control Council for Information Technology Equipment) standard developed by a voluntary restraint group. In addition, for example, in the United States, there is the FCC (Federal Communications Commission) standard. Moreover, for example, in Europe, there is EN (European Norm) standard.
These limit values (in other words, EMI standard values) are decided as the circumstances of radio waves in the individual countries and regions are reflected. Therefore, the EMI standard values are varied depending on the countries and regions, and it is often necessary to change the settings of an electronic appliance in order to follow the EMI standard values.
However, in association with the provision of high performance and complex mechanisms for electronic appliances nowadays, another problem arises. In other words, in the consequence of the provision of high performance and complex mechanisms for electronic appliances, such a problem arises that even the same electronic appliances have different levels of extraneous emission depending on the differences in the operation details and circuit systems of the electronic appliances. As the result, even though an EMI filter is used, it is difficult to reliably remove radiation interference waves.
Then, JP-A-11-206107 (Patent Reference 1) discloses a technique in which connections between a power source and a ground are controlled separately depending on circuit systems in order to meet the EMI standard of the countries that provide the levels of extraneous emission of electronic appliances.